With the rapid development of Internet services and multimedia applications, a traffic volume of a network is rapidly expanding at an exponential rate, and therefore the network is required to have a high-bit-rate data transmission capability and a high throughput cross-connect capability. Therefore, a fiber optic communications technology starts to infiltrate a communications network. In addition, because an optical signal of an all optical network (AON) exists always in a form of light instead of undergoing optical-to-electrical conversion and electrical-to-optical conversion when transmitted and switched in the network, there is a tendency for fiber optic communications to develop towards the all optical network in an all-round manner.
An optical cross-connection (OXC) is an important part of the all optical network. Main functions of an OXC node include wavelength dimension switching, spatial dimension switching, local wavelength add/drop, and the like. The network requires the OXC node to be high in a switching capacity, transparent to a wavelength and a data format, low in a congestion rate, low in power consumption, high in an integration level, low in costs, and the like. A key component of the OXC node, that is, an optical switching apparatus, such as an optical switch, is mainly configured to switch an optical signal, that is, output a given quantity of input signals from corresponding output ports according to a given mapping relationship.
Currently, there are mainly two types of optical switching apparatuses applied to a wavelength division multiplexing (WDM) network. One is a 3-dimensional micro-electro-mechanical system (3D-MEMS) optical switch based on a micromirror reflection technology. The optical switch makes input optical signals incident in parallel on an MEMS micromirror array after the input optical signals are collimated by a collimator array. Under control of a control signal, a micromirror of the MEMS micromirror array rotates an orientation and reflects incident light into a corresponding output port, and then focuses the incident light on an output port array by using a converging lens. Therefore, the 3D-MEMS optical switch based on the micromirror reflection technology is a micro mechanical device, susceptible to mechanical vibration, and additional vibration absorbent measures need to be taken to absorb vibration.
The other common optical switching apparatus is an optical switch based on a cross-bar structure. Generally, the optical switch based on the cross-bar structure includes small switch units, and each small switch unit is of a 2×2 structure and has two states: CROSS, output and input being in a cross state (input 1→output 2; and input 2→output 1); and BAR, output and input being in a direct state (input 1→output 1; and input 2→output 2). That is, a 16×16 optical switch needs to be formed by 56 small switch units. Because the cross-bar structure optical switch has many small switch units and has a complex structure, a crosstalk easily occurs between channels. To obtain better switching performance, it is required to add more small switch units or perform algorithm optimization. In addition, the cross-bar structure optical switch easily causes congestion.
Therefore, the existing optical switching apparatus applied to a WDM network either has a congestion problem due to a complex structure, or requires a relatively stable environment. In addition, the existing optical switching apparatus may not be effectively applied to an orbital angular momentum (OAM) network.